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United States Patent |
5,732,570
|
Tomatsu
,   et al.
|
March 31, 1998
|
Thermal expansion valve and air conditioning apparatus using the same
Abstract
A thermal expansion valve for automotive coolant systems which is
significantly more compact than previously developed expansion values. The
housing of the expansion valve is divided into a first housing formed in a
cylindrical shape with a bottom and a second housing formed in a columnar
shape. The first housing is fit into the second housing, and both are
integrally connected to each other. A temperature sensing mechanism having
a temperature sensing chamber and an expansion mechanism for adjusting an
opening degree of a throttle passage in accordance with an evaporator
outlet temperature sensed by the temperature sensing means are disposed in
the second housing. First and fourth joint portions connected to inlet and
outlet refrigerant pipes of the evaporator, respectively, are at the
bottom of the first housing. On the other hand, second and third joint
portions connected to a compressor suction side refrigerant pipe and a
high-pressure side refrigerant pipe from a receiver, respectively, are at
an outer surface of the second housing. In this manner the overall size of
the expansion valve is reduced considerably, thus saving valuable space in
an engine compartment of a vehicle.
Inventors:
|
Tomatsu; Yoshitaka (Chiryu, JP);
Kuroda; Yasutaka (Anjo, JP);
Kakehashi; Nobuharu (Toyoake, JP);
Kishita; Hiroshi (Anjo, JP);
Yamanaka; Yasushi (Nakashima-gun, JP);
Fujiwara; Kenichi (Kariya, JP)
|
Assignee:
|
Denso Corporation (Kariya, JP)
|
Appl. No.:
|
755212 |
Filed:
|
November 22, 1996 |
Foreign Application Priority Data
| Nov 24, 1995[JP] | 7-306120 |
| Dec 18, 1995[JP] | 7-329165 |
| Oct 23, 1996[JP] | 8-280981 |
Current U.S. Class: |
62/527; 62/222 |
Intern'l Class: |
F25B 041/06 |
Field of Search: |
62/216,222,224,225,528,504,527
|
References Cited
U.S. Patent Documents
3537645 | Nov., 1970 | Treder | 62/224.
|
3592018 | Jul., 1971 | Widdowson | 62/222.
|
3738119 | Jun., 1973 | Scherer et al. | 62/217.
|
3785554 | Jan., 1974 | Proctor | 236/34.
|
3800551 | Apr., 1974 | Weibel et al. | 62/217.
|
Foreign Patent Documents |
A-5-278455 | Oct., 1993 | JP.
| |
Primary Examiner: Doerrler; William
Attorney, Agent or Firm: Harness, Dickey & Pierce, PLC
Claims
What is claimed is:
1. A thermal expansion valve for expanding refrigerant and for forming
therein a refrigerant passage for a refrigerating apparatus including a
compressor and an evaporator, said valve comprising:
a first, cylindrical housing member having a bottom at a first end and an
opening at a second end thereof;
a second, columnar housing member fit into and integrally coupled to said
first housing member from the second end of said first housing member in
an axial direction of said first housing member;
a first joint portion at said first end of said first housing member for
communicating with said evaporator outlet side, through which refrigerant
from said outlet of said evaporator flows into said first housing member;
a temperature sensing mechanism, in said second housing member, having a
temperature sensing chamber for sensing a temperature of the refrigerant
from said evaporator outlet side;
a second joint portion, on an outer end surface of said second housing
member, for communicating with a suction side of said compressor, through
which the refrigerant from said evaporator outlet side flows into said
compressor suction side;
a third joint portion, on said second housing member outer end surface,
through which high-pressure side liquid refrigerant flows into said second
housing member;
an expansion mechanism, in said second housing member, for decompressing
and expanding the high-pressure side liquid refrigerant in accordance with
a temperature of the refrigerant sensed by said temperature sensing
mechanism; and
a fourth joint portion on said first end side of said first housing member,
for communicating with an inlet side of said evaporator, through which the
refrigerant expanded by said expansion mechanism flows into said
evaporator inlet side.
2. A thermal expansion valve according to claim 1, further comprising a
sealing member in an engagement portion between an inner surface of said
first housing member and an outer peripheral surface of said second
housing member to maintain airtightness.
3. A thermal expansion valve according to claim 1, wherein said temperature
sensing mechanism and said expansion mechanism are disposed in said second
housing member in a direction which perpendicularly crosses an engagement
face of said first and second housing members.
4. A thermal expansion valve according to claim 1, wherein said first
housing member is directly coupled to said evaporator.
5. A thermal expansion valve according to claim 1, wherein said first and
second joint portions are provided on said bottom of said first housing.
6. A thermal expansion valve according to claim 1, wherein said expansion
mechanism includes:
a pressure responsive member moveable in response to a temperature of the
refrigerant sensed by said temperature sensing mechanism; and
a valve body for controlling an opening degree of a throttle passage, for
decompressing and expanding the high-pressure side liquid refrigerant,
said valve body being displaced in accordance with a displacement of said
pressure responsive member.
7. A thermal expansion valve according to claim 1, wherein said expansion
mechanism is elastically supported in said first and second housing
members.
8. A thermal expansion valve according to claim 7, wherein said expansion
mechanism is supported by a rubber supporting member in second first and
said housing members.
9. A thermal expansion valve according to claim 6, further comprising:
a pressure responsive member, within a case of said temperature sensing
mechanism, for being displaced responsive to a temperature of the
refrigerant sensed by said temperature sensing mechanism; and
a valve body of said expansion mechanism, integrally joined to said
pressure responsive member, for controlling an opening degree of a
throttle passage, for decompressing and expanding the high-pressure side
liquid refrigerant, said valve body being displaced in accordance with a
displacement of said pressure responsive member;
wherein said temperature sensing mechanism and said valve body are
integrally moved in accordance with the displacement of said pressure
responsive member.
10. A thermal expansion valve according to claim 9, further comprising a
rubber supporting member for supporting said expansion mechanism in said
first and said housing members elastically.
11. A thermal expansion valve according to claim 10, wherein said rubber
supporting member includes a first supporting portion for said expansion
mechanism and a second supporting portion for supporting said temperature
sensing mechanism, said first and second supporting portions being
integrally formed.
12. A thermal expansion valve according to claim 10, wherein said rubber
supporting member includes therein a high-pressure side refrigerant
passage through which the high-pressure refrigerant flows and a
low-pressure side refrigerant passage through which low-pressure
refrigerant having passed through said throttle passage flows.
13. A thermal expansion valve according to claim 10, wherein a rubber
hardness of said rubber supporting member is in a range of Hs 50-70.
14. An air conditioning apparatus for a vehicle having an engine
compartment and a passenger compartment partitioned by a dashboard, said
apparatus comprising:
condensing equipment, in said engine compartment, including a compressor
for condensing refrigerant, a compressor suction side refrigerant pipe for
a suction side of said compressor and a high pressure side liquid
refrigerant pipe for high pressure side liquid refrigerant;
a cooling unit, disposed in said passenger compartment, including an
evaporator having an inlet side refrigerant pipe and an outlet side
refrigerant pipe; and
a thermal expansion valve for expanding refrigerant and for connecting
between said condensing equipment and said cooling unit, said thermal
expansion valve including:
a first, cylindrical housing member having a bottom at a first end and an
opening at a second end thereof;
a second, columnar housing member fit into and integrally coupled to said
first housing member from the second end of said first housing member in
an axial direction of said first housing member,
a first joint portion, at said first end of said first housing member, for
communicating with said evaporator outlet side pipe, through which
refrigerant from said evaporator outlet side pipe flows into said first
housing member,
a temperature sensing mechanism, in said second housing member, having a
temperature sensing chamber for sensing a temperature of the refrigerant
from said evaporator outlet side pipe,
a second joint portion, on an outer end surface of said second housing
member, for communicating with said compressor suction side, through which
the refrigerant from said outlet of said evaporator outlet side pipe flows
into said compressor suction side,
a third joint portion, on an outer end surface of said second housing
member, through which high-pressure side liquid refrigerant flows into
said second housing member,
an expansion mechanism, in said second housing member, for decompressing
and expanding the high-pressure side liquid refrigerant responsive to a
temperature of the refrigerant sensed by said temperature sensing
mechanism, and
a fourth joint portion, on said one end of said first housing member, for
communicating with said evaporator inlet side, through which the
refrigerant expanded by said expansion mechanism flows into said inlet
side pipe of said evaporator;
wherein said dashboard includes a through hole into which said thermal
expansion valve is fit with an elastic member;
said outlet side refrigerant pipe of said evaporator is coupled to said
first joint portion of said thermal expansion valve;
said compressor suction side refrigerant pipe of said condensing equipment
is coupled to said second joint portion of said thermal expansion valve;
said high-pressure side liquid refrigerant pipe of said condensing
equipment is coupled to said third joint portion of said thermal expansion
valve; and
said inlet side refrigerant pipe of said evaporator is coupled to said
fourth joint portion of said thermal expansion valve.
15. A thermal expansion valve according to claim 1, wherein said
temperature sensing mechanism and said expansion mechanism are in said
second housing member.
16. A thermal expansion valve according to claim 15, wherein said expansion
mechanism includes:
a pressure responding member for being displaced responsive to a
temperature of the refrigerant sensed by said temperature sensing
mechanism; and
a valve body for controlling an opening degree of a throttle passage formed
in said second housing member, for decompressing and expanding the
high-pressure side liquid refrigerant, said valve body being displaced
responsive to a displacement of said pressure responding member.
17. A thermal expansion valve according to claim 16, further comprising:
a pressure responding member, in a case of said temperature sensing
mechanism, for being displaced in accordance with a temperature of the
refrigerant sensed by said temperature sensing mechanism;
a valve body of said expansion mechanism, joined to said pressure
responding member of said temperature sensing mechanism, for controlling
an opening degree of a throttle passage formed in said second housing
member, for decompressing and expanding the high-pressure side liquid
refrigerant, said valve body being displaced in accordance with a
displacement of said pressure responding member;
wherein said temperature sensing mechanism and said valve body are
integrally moved in accordance with the displacement of said pressure
responding member.
18. An air conditioning apparatus according to claim 14, wherein said
temperature sensing mechanism and said expansion mechanism are provided in
said second housing member.
19. A method of assembling a thermal expansion valve, said method
comprising:
disposing an expansion mechanism in a first communication path of a
columnar housing between a joint portion for connection to a high-pressure
refrigerant line and a joint portion for connection to an evaporator inlet
so that said expansion mechanism controls the flow of a medium
therethrough;
disposing a temperature sensing mechanism in a second communication path of
said columnar housing between a joint portion for connection to an
evaporator inlet and a joint portion for connection to a compressor
suction side so that said temperature sensing mechanism moves said
expansion mechanism responsive to the temperature of a medium in said
second communication path; and
fitting said columnar housing into a hollow cylindrical housing in an axial
direction of said hollow cylindrical housing to establish an airtight seal
therebetween.
Description
CROSS REFERENCE TO THE RELATED APPLICATIONS
This application is based on and claims priority of Japanese Patent
Application Nos. Hei. 7-306120 filed on Nov. 24, 1995, Hei. 7-329165 filed
on Dec. 18, 1995, Hei. 8-280981 filed on Oct. 23, 1996, the contents of
which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a thermal expansion valve and an air
conditioning apparatus for a vehicle using the same.
2. Description of Related Art
Conventionally, there has been proposed a structure of an expansion valve
to improve a mounting performance on a vehicle, of a cooling unit and an
expansion valve in an air conditioning apparatus for a vehicle, as
disclosed in JP-A-5-278455.
According to such an expansion valve, as shown in FIGS. 12-14, a round
through hole 74 is opened in a dashboard D for partitioning an engine
compartment E and a passenger compartment R of a vehicle. A connecting
member 100 of a refrigerant pipe is fit into the through hole 74. A
housing 300 of an expansion valve 3 is provided in a resin-made round
block 101 of the connecting member 100. A temperature sensing mechanism 35
and an expanding mechanism 47 are incorporated in the housing 300.
In FIGS. 13 and 14, there are disposed a group 1 of condensing equipment
such as a compressor, a condenser, a receiver, and the like, which are
installed in the engine compartment E, a cooling unit 2 in the passenger
compartment R, and an evaporator 21.
According to such a structure, since the connecting member 100 of the
refrigerant pipes and the expansion valve 3 are integrally formed, the
cooling unit 2 and the expansion valve 3 are mounted on the vehicle more
easily than a structure of a normal type in which the expansion valve 3 is
independently installed adjacent the evaporator 21 of the cooling unit 2
in the passenger compartment R. Thus, the mounting performance on a
vehicle, of the cooling unit 2 and the expansion valve 3, is improved.
According to the conventional structure, however, as shown in FIG. 13, the
temperature sensing mechanism 35 and the expansion mechanism 47 of the
expansion valve 3 are accommodated in the housing 300 from an upper
opening 301 of the vertically extended housing 300. The upper opening 301
is closed by a cover 302. A sealing portion using an O-ring 303 is
provided around the cover 302.
The expansion mechanism 47, the temperature sensing mechanism 35, and the
cover 302 having the sealing portion using the O-ring 303 are stacked up
in the height direction of the expansion valve 3 (vertical direction of
FIG. 13). There is accordingly a problem in that the height of the
expansion valve would be large naturally. Consequently, the conventional
structure has a problem in that the expansion valve is large-sized. It is
a major problem especially for an automobile having a limited installation
space.
SUMMARY OF THE INVENTION
In view of the foregoing problems, it is an object of the invention to
downsize an outer shape of a thermal expansion valve which also serves as
a connecting member of refrigerant pipes.
According to a first aspect the invention, a housing of a thermal expansion
valve is halved into first and second housing members, the housing members
are engaged with and connected to each other, and a temperature sensing
mechanism and an expansion mechanism are assembled in the second housing
member. Thus, it is not necessary to attach a cover having a sealing
mechanism to the top of the housing as in the conventional structure. The
height of the thermal expansion valve is remarkably reduced as compared
with the conventional structure. As a result, there is an effect that the
thermal expansion valve is remarkably downsized.
Although the housing of the thermal expansion valve is halved, since a
first joint portion coupled to an the outlet side of an evaporator and a
fourth joint portion coupled to an inlet side of the evaporator are
provided at one end of the first housing member, both of the first and
fourth joint portions can be easily and accurately formed. Similarly, a
second joint portion coupled to a suction side of a compressor and a third
joint coupled to a high-pressure side are provided on the surface of the
second housing member, so that both of the second and third joint portions
can be also easily and accurately formed.
The first and fourth joint portions can be airtightly connected to the
refrigerant pipes on the inlet/outlet sides of the evaporator and the
second and third joint portions can be airtightly connected to the
refrigerant pipes on the compressor suction side and the high-pressure
side without causing positional deviation. Therefore, leakage of
refrigerant from the joint portions can be certainly prevented without
especially enhancing the dimensional accuracy of the halved housing
members.
In addition, according to another aspect of the invention, the first
housing member is formed in a cylindrical shape and the second housing
member is formed in a columnar shape. Consequently, the housing of the
expansion valve has a columnar shape, and a round block as in a
conventional structure is not necessary.
According to another aspect of the invention, a member for airtightly
sealing is attached to an engagement portion of the inner surface of the
cylindrical first housing member and the peripheral surface of the
columnar second housing member. When the halved housing members are used,
the sealing member can be disposed each of the peripheral faces of the
first to fourth joint portions, so that the first and fourth joint
portions and the second and third joint portions can be adjacently
disposed. Thus, the connecting portions of the first to fourth joint
portions and the refrigerant pipes can be downsized.
According to another aspect of the invention, since the first housing
member is directly connected to the evaporator, the expansion valve and
the evaporator can be integrated. Consequently, the installation space and
the cost are reduced.
There is also provided an air conditioning apparatus for a vehicle,
including a group of condensing equipment mounted on an engine compartment
and a cooling unit mounted on a passenger compartment. In the apparatus, a
through hole is opened in a dashboard partitioning the engine compartment
and passenger compartment, and one of the above-mentioned thermal
expansion valves is fit into the through hole with an elastic member. The
size of the through hole opened in the dashboard can be reduced according
to the size of the thermal expansion valve and accordingly it becomes easy
to seal the through hole.
In the vehicle where a space is very limited, the mounting performance of
the air conditioning apparatus on the vehicle is remarkably improved by
downsizing the thermal expansion valve and the smaller through hole in the
dashboard.
BRIEF DESCRIPTION OF THE DRAWINGS
Additional objects and advantages of the present invention will be more
readily apparent from the following detailed description of preferred
embodiments thereof when taken together with the accompanying drawings in
which:
FIG. 1 is a cross sectional view showing an expansion valve according to a
first embodiment of the present invention;
FIG. 2 is a front view of the expansion valve in the first embodiment;
FIG. 3 is an exploded perspective view showing a connection structure of
the expansion valve and the refrigerant pipes in the first embodiment;
FIG. 4 is a schematic view showing an entire construction of an air
conditioning apparatus for a vehicle, employing the expansion valve in the
first embodiment;
FIG. 5 is a cross sectional view showing an expansion valve according to a
second embodiment of the present invention;
FIG. 6 is an exploded perspective view showing a connection structure of an
expansion valve and refrigerant pipes according to a third embodiment;
FIG. 7 is a schematic view showing an entire construction of an air
conditioning apparatus for a vehicle, employing the expansion valve in the
third embodiment;
FIG. 8 is a cross sectional view showing an expansion valve according to a
fourth embodiment of the present invention;
FIG. 9 is a side view of the expansion valve in the fourth embodiment;
FIG. 10 is a graph showing a relationship between the hardness of the
rubber body and the noise in the fourth embodiment;
FIG. 11 is a cross sectional view showing an expansion valve according to a
fifth embodiment of the present invention;
FIG. 12 is a schematic view showing an entire construction of an air
conditioning apparatus for a vehicle, employing the conventional expansion
valve;
FIG. 13 is a cross sectional view showing the conventional expansion valve;
and
FIG. 14 is a front view of the conventional expansion valve.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Embodiments of the present invention will be described with reference to
the drawings.
A first embodiment of the present invention will be described.
FIGS. 1 to 4 show the first embodiment. FIG. 4 schematically shows an
entire structure of an air conditioning apparatus for a vehicle. In this
embodiment, cooling equipment in the air conditioning apparatus includes a
condensing equipment group 1 mounted on an engine compartment E of the
vehicle, a cooling unit 2 mounted on a passenger compartment R of the
vehicle, and a thermal expansion valve 3 arranged in a dashboard D for
partitioning the engine compartment E and the passenger compartment R and
also serving as a connecting member of refrigerant pipes between the
engine compartment E side and the passenger compartment R side.
The condensing equipment group 1 includes a compressor 10 which is driven
by an automobile engine, a condenser 11 for cooling and condensing a
refrigerant gas discharged from the compressor 10, a receiver 12 for
storing the condensed refrigerant from the condenser 11, separating a
vapor from the refrigerant, and introducing only a liquid refrigerant to
the downstream side; and the like. The compressor 10 is intermittently
operated by an electromagnetic clutch 10a.
The cooling unit 2 includes a cooling unit case 20 made of a resin. An
evaporator 21 is incorporated in the case 20. The cooling unit 2 cools and
dehumidifies air which has been sucked from an inside/outside air
switching box 22 of the air conditioning apparatus for the vehicle and
blown by a centrifugal multiblade blower 23.
A heater unit 28 is disposed on the downstream air side of the cooling unit
2. The heater unit 28 includes a heater core 24 using hot water, an air
mix damper 25 for temperature control, a damper 26 for switching air
outlets, various air outlets 27, and the like.
FIG. 3 schematically shows a pipe connecting structure between the
evaporator 21 and the expansion valve 3. There are provided pipes 70-73
and a pipe coupling member 63. The suction side refrigerant pipe 71 of the
compressor 10 and the high pressure side liquid refrigerant pipe 72 from
the receiver 12 are screwed and fixed to a second housing 32 of the
expansion valve 3 by means of the pipe coupling member 63 and a bolt 67.
The low-pressure refrigerant pipes 70 and 73 extending from the outlet and
inlet sides of the evaporator 21 are connected to a first housing 31 of
the expansion valve 3 by brazing or the like.
The main feature of the invention is the thermal expansion valve 3. A
specific structure of the expansion valve 3 will now be described with
reference to FIGS. 1 and 2. The first and second housings 31 and 32 are
made of a light weight and corrosion-resistant metal such as aluminum. The
first housing 31 has a cylindrical shape having a bottom at one end and an
opening at the other end as shown in FIG. 1. On the bottom of the first
housing 31, there are formed a first joint portion (refrigerant inlet
portion) 311 which is connected to the low-pressure refrigerant pipe 70
from the outlet side of the evaporator 21 and a fourth joint portion
(refrigerant outlet portion) 312 which is connected to the low-pressure
refrigerant pipe 73 from the inlet side of the evaporator 21.
The fourth joint portion (refrigerant outlet portion) 312 is disposed
almost in the center of the bottom of the first housing 31. The first
joint portion (refrigerant inlet portion) 311 is disposed in a portion
biased from the center of the bottom of the first housing 31.
On the other hand, as shown in FIG. 1, the second housing 32 has a column
shape and can be inserted into the first housing 31. A second joint
portion (refrigerant outlet portion) 321 and a third joint portion
(refrigerant inlet portion) 322 are formed on the end face (surface
portion) of the second housing 32. An end of the refrigerant pipe 71 from
the compressor suction side is fit into and connected to the second joint
portion 321. An end of the high-pressure side liquid refrigerant pipe 72
from the receiver 12 is fit into and connected to the third joint portion
322.
The first and second housings 31 and 32 are screwed by a cover 33 so as not
to come off and are integrally coupled to each other. An O-ring (elastic
sealing member) 56 is disposed around the fitting face of the first and
second housings 31 and 32 to keep the airtightness from the outside.
In the second housing 32, the temperature sensing mechanism 35 and the
expansion mechanism 47 are disposed in a direction which perpendicularly
crosses the fitting face of the first and second housings 31 and 32 (i.e.,
a direction which perpendicularly crosses the axial direction of the
housings 31 and 32). In the second housing 32, a chamber 35a for housing
the temperature sensing mechanism 35 is connected to a low-pressure side
refrigerant passage 34. One end of the low-pressure side refrigerant
passage 34 is connected to the first joint portion 311 and the other end
is connected to the second joint portion (refrigerant outlet portion) 321.
The temperature sensing mechanism 35 includes an upper metal diaphragm case
36, a lower metal diaphragm case 37, and a metal diaphragm (pressure
interlocking member) 38 which is sandwiched and fixed between the cases 36
and 37. The diaphragm cases 36 and 37 and the diaphragm 38 are made of a
corrosion-resistant metal such as stainless steel and are integrally
joined by welding or the like.
In the lower diaphragm case 37, a low-pressure introducing hole 41 is
formed at a portion below the diaphragm 38. Through the low-pressure
introducing hole 41, a refrigerant pressure (low pressure) in the
low-pressure side refrigerant passage 34 is introduced into a pressure
chamber 42 between the diaphragm case 37 and the diaphragm 38.
Activated charcoal (not shown) and the same refrigerant gas as that in a
refrigerating cycle are sealed in a temperature sensing chamber 43 formed
between the upper diaphragm case 36 and the diaphragm 38. It may be
acceptable that the activated charcoal (not shown) is not sealed but only
the refrigerant gas is sealed in the temperature sensing chamber 43. Since
the same refrigerant as that in the refrigerating cycle is sealed in the
temperature sensing chamber 43, the pressure in the temperature sensitive
chamber 43 indicates a saturation pressure according to the surrounding
temperature of the refrigerant (the temperature of the refrigerant flowing
from the low-pressure side refrigerant passage 34 to the chamber 35a).
A screw member 54 is disposed to face the upper metal diaphragm case 36. By
screwing the screw member 54 into a screw hole 54a, the upper metal
diaphragm case 36 is pushed downward. The lower metal diaphragm case 37 is
consequently pressed against a supporting face 35b of the housing chamber
35a of the second housing 32, thereby fixing the temperature sensing
mechanism 35 to the second housing 32.
A metal contacting member 45 which is displaced according to displacement
of the diaphragm 38 is disposed in the pressure chamber 42 within the
lower diaphragm case 37. One end of an axis portion 45a which is
separately formed comes into contact with the contacting member 45. The
axis portion 45a is held to slide along a guide hole 46 formed in the
second housing 32.
An O-ring (elastic sealing member) 45b keeps airtightness between the axis
portion 45a and the guide hole 46. A spherical valve element 49 of the
expansion mechanism 47 comes into contact with the other end of the axis
portion 45a. The opening of a throttle passage 39 is adjusted by the valve
element 49. The upstream side of the throttle passage 39 is connected to
the third joint portion (refrigerant inlet portion) 322 via a
high-pressure chamber 44. The portion 322 is connected to the
high-pressure side liquid refrigerant pipe 72. The downstream side of the
throttle passage 39 is communicated with the fourth joint portion
(refrigerant outlet portion) 312 through a low-pressure chamber 40. The
portion 312 is connected to the low-pressure refrigerant pipe 72 on the
inlet side of the evaporator 21.
The spherical valve element 49 is joined to a spring seat plate 50 by means
of spot welding or the like. The spring force of a coil spring 51 acts on
the valve element 49 through the seat plate 50. One end of the coil spring
51 is held by the seat plate 50 and the other end is held by a spring
holding cylinder 52.
The spring holding cylinder 52 is fixed to the wall surface of the second
housing 32 so that the position can be adjusted by a screw. By adjusting
the installation position of the spring holding cylinder 52 by the screw,
the spring force acting on the valve element 49 is adjusted and opening
valve characteristics of the valve element 49 are adjusted. In this way,
the degree of superheating of the refrigerant from the outlet of the
evaporator 21 can be adjusted.
By arranging an O-ring (elastic sealing member) 52a between the spring
holding cylinder 52 and the wall face of the second housing 32, the
high-pressure chamber 44 is airtightly maintained against the low-pressure
side.
Further, a cylinder portion 40a is formed around the low-pressure chamber
40 in the second housing 32. A cylinder portion 312a is formed around the
fourth joint portion (refrigerant outlet portion) 312 on the bottom of the
first housing 32. The cylinder portion 40a of the second housing 32 is
engaged with the outer periphery portion of the cylinder portion 312a. The
engagement faces of the cylinder portions 40a and 312a form stepped
shapes. By arranging an O-ring (elastic sealing member) 312b to the
stepped portions, the fourth joint portion 312 and the low-pressure side
refrigerant passage 34 are coupled to keep airtightness therebetween.
The end of the cylinder portion 40a of the second housing 32 comes into
contact with the bottom of the first housing 31, thereby determining the
assembling position in the axial direction of the first and second
housings 31 and 32. Therefore, the cylinder portion 40a also serves as a
positioning member.
A screw hole 57 is opened on the end face of the second housing 32. By
screwing the bolt 67 shown in FIG. 3 into the screw hole 57, the
refrigerant pipe 71 on the suction side of the compressor 10 and the
high-pressure side liquid refrigerant pipe 72 from the receiver 12 are
screwed and fixed to the second housing 32 with the pipe coupling member
63.
By connecting the thermal expansion valve 3 to the refrigerant pipes 70 to
73 as mentioned above, the thermal expansion valve 3 also serves as a
connecting member which connects between the refrigerant pipe on the
engine compartment R side and the refrigerant pipe on the passenger
compartment R side.
The circular through hole 74 is opened in the dashborad D. An elastic
grommet 75 made of rubber is attached to the through hole 74. The first
housing 31 of the thermal expansion valve 3 is press-fit into the center
hole of the grommet 75 and is held.
A method of assembling the thermal expansion valve 3 in this embodiment
will be described. First, in a single state of the second housing 32, the
expansion mechanism 47 is accommodated and assembled in the high-pressure
chamber 44 of the second housing 32. That is, the spherical valve element
49 of the expansion mechanism 47, the spring seat plate 50 which is
integral with the valve element 49, the coil spring 51, and the spring
holding cylinder 52 are accommodated and the spring holding cylinder 52 is
screwed to the wall face of the second housing 32.
Subsequently, the axis portion 45a of the temperature sensing mechanism 35
is assembled in the guide hole 46 through the screw hole 54a into which
the screw member 54 has not been attached yet. Then, the contacting member
45 and the diaphragm cases 36 and 37 to which the diaphragm 38 has been
attached are accommodated in the housing chamber 35a of the temperature
sensing mechanism 35 from the left opening shown in FIG. 1.
The screw member 54 is screwed into the screw hole 54a, thereby pressing
the diaphragm cases 36 and 37 against the supporting face 35b of the
housing chamber 35a and fixing the diaphragm cases 36 and 37 in the
housing chamber 35a.
Consequently, the temperature sensing mechanism 35 and the expansion
mechanism 47 are assembled in the second housing 32. By adjusting the
screwing position of the spring holding cylinder 52 in such a state, the
preset installation load of the coil spring 51 is adjusted, thereby making
it possible to adjust the degree of superheating of the refrigerant from
the outlet of the evaporator, which is controlled by the thermal expansion
valve 3, to a predetermined value.
After attaching the O-ring 53 in the groove on the periphery of the second
housing 32, the second housing 32 is fit into the first housing 31. The
housings 31 and 32 are screwed by the cover 33 and integrally coupled.
A method of mounting the expansion valve of the invention on the vehicle
will be described. Firstly, the first housing 31 is preliminarily
integrated to the refrigerant pipes 70 and 73 on the evaporator 21 side by
a connecting means such as brazing. Then, as shown in FIG. 4, the rubber
grommet 75 is directly press-fit into the through hole 74 of the dashboard
D, and the first housing 31 is press-fit into the center hole of the
rubber grommet 75 from the passenger compartment R side. The second
housing 32 is fit into the first housing 31 by an operation from the
engine compartment E side, and both housings 31 and 32 are screwed and
integrated with other by the cover 33.
According to such an assembling method, at maintaining the expansion valve,
the first housing 31 is fit in the through hole 74 portion of the
dashboard D while being connected to the refrigerant pipes 70 and 73 on
the evaporator 21 side. On the other hand, the second housing 32 can be
taken out from the first housing 31 by the operation from the engine
compartment E side. Accordingly, the temperature sensing mechanism 35 in
the second housing 32 and the expansion mechanism 47 can be simply
checked, repaired or replaced, thereby improving the maintaining
performance of the expansion valve 3.
An operation of the embodiment having the above structure will be
described.
The gas refrigerant evaporated in the evaporator 21 of the cooling unit 2
flows through the refrigerant pipe 70 into the low-pressure side
refrigerant passage 34 from the first joint portion (refrigerant inlet
portion) 311 of the first housing 31 and passes through the passage 34.
The temperature of the refrigerant passing the passage 34 is sensed by the
temperature sensing chamber 43 and the pressure in the temperature sensing
chamber 43 is set to a pressure corresponding to the temperature of the
refrigerant.
The refrigerant pressure of the low-pressure side refrigerant passage 34 is
introduced through the low pressure introducing hole 41 into the pressure
chamber 42 below the diaphragm 38. Since the spring force of the spring 51
acts on the diaphragm 38 via the valve element 49, axis portion 45a,
contacting member 45, and the like, the diaphragm 38 is displaced
according to these forces. The valve element 49 is moved to a position
according to the displacement of the diaphragm 38, thereby adjusting the
opening degree of the throttle passage 39.
By the adjustment of the opening with the valve element 49, the refrigerant
from the outlet of the evaporator is maintained to a predetermined degree
of superheating which is determined by the spring force (preset
installation load) of the spring 51.
The housing of the thermal expansion valve 3 is halved, the columnar second
housing 32 is fit into the cylindrical first housing 31, and the
temperature sensing mechanism 35 is assembled in the second housing 32.
Therefore, it is not necessary to attach a cover having a sealing
mechanism to the top of the housing as in the conventional structure, so
that the height (vertical dimension in FIG. 1) of the thermal expansion
valve 3 can be reduced.
Since the expansion valve 3 of the embodiment has a columnar shape, a round
block in the conventional structure is not necessary. The expansion valve
3 can be directly press-fit into and held in the rubber grommet 75. The
through hole 74 opened in the dashboard D can be accordingly made smaller
and the sealing at the through hole 74 portion is simplified.
A second embodiment of the present invention will be described with
reference to FIG. 5.
As a connecting structure of the first and second housings 31 and 32, these
housings 31 and 32 are tightly fixed directly by a bolt 61 without using
the cover 33 to be screwed as in the first embodiment. The remaining
structure is similar to that of the first embodiment.
A third embodiment of the present invention will be described with
reference to FIGS. 6 and 7.
In FIGS. 6 and 7, the expansion valve 3 is directly connected to the
evaporator 21. The first housing 31 of the expansion valve 3 is directly
connected to an end plate (not shown) of the evaporator 21 by brazing or
the like. The first and fourth joint portions 311 and 312 of the first
housing 31 are coupled to the outlet side refrigerant pipe 70 and the
inlet side refrigerant pipe 73 of the evaporator 21, which are formed on
the end plate of the evaporator 21.
According to the third embodiment, only the first housing 31 of the
expansion valve 3 is directly brazed to the end plate (not shown) of the
evaporator 21. Then, the second housing 32 having therein the temperature
sensing mechanism 35 and the expansion mechanism 47 is coupled to the
first housing 31.
In the third embodiment, it may be also acceptable that the first housing
31 is directly connected to the end plate of the evaporator 21 by screwing
or the like after the assembly of the entire expansion valve 3 has been
completed.
The outer shape of each of the housings 31 and 32 is not limited to the
regular cylindrical one as shown in FIG. 2, but may be changed to an oval,
rectangle, polygon, or the like.
As sealing means of the engagement face between the housings 31 and 32, a
face sealing structure in which a stepped face is press-contacted with the
engagement face of the housings 31 and 32 may be also used without using
the O-ring 53.
In the first embodiment shown in FIG. 4, when the expansion valve 3 is
assembled to the dashboard D, the columnar outer shape of the housings 31
and 32 of the expansion valve 3 is directly fit into the rubber grommet
75. However, it may be acceptable that the housings 31 and 32 have a shape
other than the columnar shape, such as a polygonal shape, a round body
made of resin is integrally provided on the outer side of the polygonal
housings 31 and 32 in the same manner as in JP-A-5-278455, and the round
body is fit into the grommet 75 made of rubber.
In the foregoing embodiment, the first and fourth joint portions 311 and
312 are disposed on the bottom formed at one end of the first housing 31
however, the first and fourth joint portions 311 and 312 may be disposed
on an outer peripheral surface at one end of the first housing 31.
A fourth embodiment of the present invention will be described with
reference to FIGS. 8 and 9.
The description of the same or equivalent elements as those in the
foregoing embodiments is omitted here. The feature of this embodiment will
be described.
A first housing 131 and a second housing 132 are used in the embodiment in
place of the first and second housings 31 and 32 in the foregoing
embodiment. The first and second housings 131 and 132 are screwed by the
cover 33 so as not to come off in the same manner as in the foregoing
embodiment. A temperature sensing mechanism 135 disposed in the housings
131 and 132 has an upper diaphragm case 136, a lower diaphragm case 137
and a metal diaphragm which is sandwiched and fixed between the cases 136
and 137.
The lower diaphragm case 137 has a cup-shaped portion 137a extending in the
downward direction of FIG. 8. A throttle passage 139 of the refrigerant is
formed on the bottom of the cup-shaped portion 137a. A refrigerant outflow
hole 40 is formed on the side face (circumferential face) of the
cup-shaped portion 137a. In the lower diaphragm case 137, at a portion
located below the diaphragm 38, the low-pressure introducing hole 41 from
which the refrigerant pressure (low pressure) in the low pressure side
refrigerant passage 34 is introduced is formed in a pressure chamber 143a
disposed between the diaphragm case 137 and the diaphragm 38.
The activated charcoal 42 is sealed in a temperature sensing chamber 143
formed between the upper diaphragm case 136 and the diaphragm 38. After
the same refrigerant gas as the one in the refrigerating cycle is sealed,
the opening of the upper diaphragm case 136 is sealed with a cover 144 by
brazing or the like.
A metal contacting member 145 which is displaced according to the
displacement of the diaphragm 38 is disposed in the pressure chamber 143a
in the lower diaphragm case 137. The contacting member 145 has an axis
portion 145a which is held to slide along a resin-made guide 146 which is
press fit to the inner wall face of the cup-shaped portion 137a of the
lower diaphragm case 137.
An O-ring 145b keeps airtightness between the axis portion 145a of the
contacting member 145 and the guide 146. One end of a valve rod 148 of an
expansion mechanism 147 comes into contact with the contacting member 145.
The valve rod 148 is slidably fit into a through hole 146a opened in the
guide 146.
A passage cylinder 153 is integrally attached to the outer wall face of the
bottom of the cup-shaped portion 137a of the lower diaphragm case 137. A
spring holding cylinder 152 is fixed to the passage cylinder 153 by a
screw. By adjusting the installation position of the spring holding
cylinder 152 by the screw, the spring force acting on the valve element 49
is adjusted and the opening valve characteristics of the valve element 49
are adjusted. Thus, the degree of superheat of the refrigerant from the
outlet of the evaporator 21 can be adjusted.
A passage hole 153a is formed on the side face (circumferential face) of
the passage cylinder 153. The passage hole 153a connects a high pressure
space 155 formed in the spring holding cylinder 152 with the passage
cylinder 153.
A temperature sensing mechanism 135 and the expansion mechanism 147 are
integrally joined in a body (supporting member) 154 made of rubber by
press-fitting or baking. In more detail, the cup-shaped portion 137a of
the lower diaphragm case 137, passage cylinder 153 and spring holding
cylinder 152 in the temperature sensing mechanism 135 and the expansion
mechanism 147 are integrally joined within the rubber body 154 by
press-fitting or baking so that all of the temperature sensing mechanism
135 and expansion mechanism 147 are held by the rubber body 154.
Since the body 154 is used in a refrigerant atmosphere including
lubricating oil of the compressor, it may be preferably made of a rubber
material which is not easily deteriorated by the lubricating oil and the
refrigerant and has swelling-resistant and contraction-resistant
characteristics. Specifically, ethylene propylene (EPDM) rubber is
preferable.
A high-pressure side refrigerant passage 154a and a low-pressure side
refrigerant passage 154b are formed in the body 154. A second refrigerant
inflow hole 322 opened in the second housing 132 is connected to the
high-pressure space 155 through the high-pressure side refrigerant passage
154a. The high-pressure liquid refrigerant from the high-pressure side
refrigerant pipe 72 passes through the second refrigerant hole 322,
high-pressure side refrigerant inflow passage 154a, high-pressure space
155 and passage hole 153a and reaches the space in the passage cylinder
153 (i.e., the space around the valve element 49).
A refrigerant outflow hole 40 opened in the cup-shaped portion 137a of the
lower diaphragm case 137 is connected to the first refrigerant outflow
hole 312 through the low-pressure side refrigerant passage 154b of the
body 154.
The body 154 is sandwiched between the first and second housings 131 and
132 while being compressed by a predetermined amount. Consequently, all of
the temperature sensing mechanism 135 and the expansion mechanism 147 are
elastically supported (rubber-floated) in the housings 131 and 132 by the
rubber body 154.
An annular concave groove 132a is formed at a portion of the second housing
132 which is inserted into the first housing 131. An O-ring 156 is fit
into the concave groove 132a.
According to the expansion valve having such a structure, when the
high-pressure liquid refrigerant from the high-pressure chamber 155 passes
through a throttle passage 139 during the operation, the high-pressure
refrigerant is rapidly decompressed and expanded. The valve element 49 is
influenced by the rapid decompressing and expanding actions of the
refrigerant in the throttle passage 139 and repeats fine vibration.
The vibration of the valve element 49 is transmitted to the valve rod 148
connected to the valve element 49, the metal contacting member 145 in
contact with the valve rod 148, the metal diaphragm 38 in contact with the
contacting member 145, and further to the diaphragm cases 136 and 137
fixedly holding the peripheral portion of the diaphragm 38.
Since the temperature sensing mechanism 135 and the expansion mechanism 147
are elastically supported (rubber floated) in the housings 131 and 132 by
the rubber body 154, the vibration is absorbed by the rubber body 154.
Consequently, the transmission of the vibration to the housings 131 and
132 is effectively reduced.
Therefore, noises in the room due to propagation of the vibration of the
housings 131 and 132 through the refrigerant pipes and the like to the
evaporator 21 and the vibration of the refrigerant pipes can be
effectively reduced. Since the diaphragm cases 136 and 137 which mainly
generates the transmission sound are accommodated in the housings 131 and
132, the noises released to the passenger compartment by the transmission
sound can be also effectively reduced. Thus, the thermal expansion valve
with low noise can be provided.
By using the first and second housings 131 and 132, an equivalent effect to
that of the foregoing embodiment can be obtained.
In the fourth embodiment, in order to stabilize the support of the
temperature sensing mechanism 135 and the expansion mechanism 147, a
rubber body may be additionally installed in portions, for instance,
between the upper diaphragm case 136 of the temperature sensing mechanism
135 and the inner wall face of the first housing 131 and between the
spring holding cylinder 152 of the expansion mechanism 147 and the inner
wall face of the first housing 131.
FIG. 10 is a graph of experimental results showing the relationship between
hardness of the rubber material used for the rubber body 154 and the noise
of the expansion valve. The experiment conditions are those at the time
when the refrigerating cycle is started; the cycle high pressure is 12
kg/cm.sup.2, the cycle low-pressure is 3 kg/cm.sup.2, and subcooling of
the liquid refrigerant flowing in the expansion valve 3 is 15.degree. C.
Conditions of noise measurement are that a microphone is installed at a
position which is apart from the expansion valve 3 by 120 mm in a
soundproof room, a noise level meter is set to the A-weighted sound
pressure level, and an average value of noise in an audio frequency range
from 20 Hz to 20 kHz is measured.
As understood from the graph, it is effective to enhance the effect of
noise reduction that the hardness of the rubber material is set to a level
equal to or less than Hs 70.
When the hardness of the rubber material used for the rubber body 154 is
greatly reduced, the support of the temperature sensing mechanism 135 and
the expansion mechanism 147 becomes unstable. A sealing function of the
connecting portions of the refrigerant passages 154a and 154b provided in
the rubber body 154 and the refrigerant passage holes 312 and 322 on the
housings 131 and 132 sides deteriorates. Consequently, the lower limit of
the hardness of the rubber material is preferably set to Hs 50 or larger
in order to stabilize the support of the mechanisms 135 and 147 and to
secure the sealing performance of the passage connecting portions.
Thus, in practice, it is preferable to set the hardness of the rubber
material used for the rubber body 154 within a range from Hs 50 to 70.
FIG. 10 shows comparison data when the rubber body 154 is replaced with an
aluminum body.
A fifth embodiment of the present invention will be described with
reference to FIG. 11.
In FIG. 11, the arrangement of a temperature sensing mechanism 235 and a
spring 251 are changed, and the temperature sensing mechanism 235 itself
is movably disposed. A refrigerant pressure (that is, the refrigerant
pressure from the outlet side of the evaporator) of the low-pressure side
refrigerant passage 34 is introduced through a plurality of through holes
237b (corresponding to the low-pressure introducing hole 41 in the fourth
embodiment) opened in a diaphragm case 237 into a lower pressure chamber
243a formed by a lower diaphragm case 237 and the diaphragm 38.
A contacting member 245 which is displaced according to displacement of the
diaphragm 38 is disposed in the pressure chamber 243a. The contacting
member 245 is made of a metal such as stainless steel, aluminum, or the
like and is formed in a disk shape. One face (top face) of the disk shape
comes into contact with the diaphragm 38.
A plurality of columnar leg portions 245c are integrally formed from the
other face (under face) of the disk-shaped contacting member 245.
The columnar leg portions 245c are slidably fit into the through holes 237b
of the lower diaphragm case 237. The end (lower end) of each of the
columnar leg portions 245c of the contacting member 245 comes into contact
with a metal pressed seating 460 which is joined to the rubber body 254 by
baking.
Specifically, the length of the columnar leg portion 245c of the contacting
member 245 is set such that the end comes into contact with the seating
460 before the lower diaphragm case 237 comes into contact with the
seating 460.
The valve element 49 is made of a metal such as stainless steel and is
formed in a sphere shape. One end of a valve rod 248 made of a metal such
as stainless steel is integrally joined to the spherical valve element 49
by welding or the like. The other end of the valve rod 248 is integrally
connected to the lower diaphragm case 237 by welding, caulking, or the
like.
The lower diaphragm case 237 and the valve rod 248 may be also formed as an
integral part by cutting, not using the structure of connecting the
separate parts.
The seating 460 has a cup-shaped portion 460a extending downwardly from the
center portion of the disk plate. The valve rod 248 is slidably fit into
the cup-shaped portion 460a. An O-ring (elastic seal member) 460b keeps
airtightness in the engagement portion between the valve rod 248 and the
cup-shaped portion 460a. A throttle passage 239 is formed on the bottom of
the cup-shaped portion 460a of the seating 460 and the refrigerant outflow
hole 40 is opened on the side face portion (circumferential wall portion)
of the cup-shaped portion 460a.
A metal cover 252a is fixed to the seating 460 by caulking. The metal cover
252a has a plurality of through holes 521 through which the outside and
inside are connected to each other. The low-pressure refrigerant of the
low-pressure side refrigerant passage 34 flows through the through holes
521 to a portion around the diaphragm cases 236 and 237.
The coil spring 251 is disposed on the upper diaphragm case 236. A spring
holder 252c supports the upper end of the coil spring 251. The position of
the spring holder 252c is adjusted with respect to the metal cover 252a as
a reference face by a screw 252b screwed into the metal cover 252a.
Since the temperature sensing mechanism 235 is movably disposed to be apart
from the housings 231 and 232 in the embodiment, the expansion mechanism
247 portion is elastically supported (rubber floated) in the housings 231
and 232 by the rubber body 254.
An operation of the fifth embodiment having such a structure will be
described. The gas refrigerant evaporated in the evaporator 21 of the
cooling unit 2 flows in the low-pressure side refrigerant passage 34 from
the refrigerant inflow hole 311 of the first housing 231 and passes
through the passage 34. At that time, the temperature of the refrigerant
passing in the passage 34 is transmitted to a temperature sensing chamber
243 through the through holes 521. The pressure in the temperature sensing
chamber 243 is set to a pressure corresponding to the temperature of the
refrigerant.
The refrigerant pressure of the low-pressure side refrigerant passage 234
is introduced through the through holes 237b into the pressure chamber
243a below the diaphragm 238. When the temperature of the refrigerant in
the low-pressure side refrigerant passage 234 is increased and the
pressure in the temperature sensing chamber 243 is increased, the
diaphragm 38 presses the top face of the contacting member 245 toward the
lower part of FIG. 11.
However, since the leg portions 245c of the contacting member 245 already
come into contact with the seating 460, the contacting member 245 cannot
be moved toward the lower part of FIG. 11. Since the leg portions 245c of
the contacting member 245 are slidably fit into the through holes 237a of
the diaphragm case 237, "the pressing force from the diaphragm 238 to the
contacting member 245" generated by the rise in pressure in the
temperature sensing chamber 243 acts as a force for pressing the entire
temperature sensing mechanism 235 in the upward direction of FIG. 11 by
using the contacting portions of the leg portions 245c of the contacting
member 245 and the seating 460 as a fulcrum.
Since the spring force to the bottom of FIG. 11 acts on the temperature
mechanism 235 by the coil spring 251, the coil spring 251 is contracted as
the temperature sensing mechanism 235 is moved in the upward direction in
FIG. 11 and the spring force is increased. The temperature sensing
mechanism 235 is moved in the upward direction of FIG. 11 until the spring
force and the "pressing force from the diaphragm 38 to the contacting
member 245" are balanced.
The valve element 49 is integrally connected via the valve rod 248 to the
lower diaphragm case 237 of the temperature sensing mechanism 235, so that
the valve rod 248 and the valve rod 49 are moved integrally with the
temperature sensing mechanism 235. The valve element 49 increases the
opening degree of the throttle passage 239 as the valve element 49 is
moved in the upward direction of FIG. 11. The flow of the refrigerant
passing through the throttle passage 239 is increased, so that the degree
of superheat of the gas refrigerant at the outlet of the evaporator 21 is
maintained at a predetermined value.
On the contrary, when the temperature of the refrigerant in the
low-pressure side refrigerant passage 34 is decreased and the pressure in
the temperature sensing chamber 243 is reduced, the "pressing force from
the diaphragm 38 to the contacting member 245" is reduced, and the whole
temperature sensing mechanism 235 is pressed by the spring force of the
coil spring 251 in the downward direction of FIG. 11, so that the valve
element 49 decreases the opening degree of the throttle passage 239.
The target degree of superheating of the gas refrigerant at the outlet of
the evaporator 21 can be changed by adjusting the spring force of the coil
spring 251.
Since the expansion mechanism 247 portion is elastically supported (rubber
floated) in the housings 231 and 232 by the rubber body 254, the noise of
the expansion valve can be lowered also in the embodiment.
By using the first and second housing cases 231 and 232, an effect similar
to that of the first embodiment can be obtained.
Although the metal cover 252a is fixed to the seating 460 by the caulking,
the spring holder 252c is held by the cover 252a, and the upper end of the
coil spring 251 is supported by the spring holder 252c in the fifth
embodiment, the cover 252a may be supported by the first housing 231 in
place of the seating 460.
Although the present invention has been fully described in connection with
the preferred embodiments thereof with reference to the accompanying
drawings, it is to be noted that various changes and modifications will
become apparent to those skilled in the art. Such changes and
modifications are to be understood as being included within the scope of
the present invention as defined in the appended claims.
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